Surface slip variability on strike‐slip faults
Surface slip variability on strike‐slip faults
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DOI：
10.1002/esp.5294
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发表时间：
2021-11
影响因子：
3.3
通讯作者：
N. Reitman;K. Mueller;G. Tucker
中科院分区：
文献类型：
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作者：
N. Reitman;K. Mueller;G. Tucker
走滑地震中的滑动沿断层在空间上是可变的，但短长度尺度上的变化程度是破裂过程固有的，或者是由解释和测量引入的，目前还没有量化。在这项研究中，我们通过比较数值景观演化模型和最近手工测量的走滑断层破裂和图像相关，研究了解释误差对地表滑动分布的表观短波变异性的影响。手工测量的63次走滑地震的地表滑动分布的平均空间变异性（CVslip - spatial =标准差/平均值）为0.43-0.52，总范围为0.14-1.14。在模拟断层恒定滑动的数值模型中，偏移地貌标记物的位移测量在手工测量时具有~ 0.25-0.40的平均空间变异性，而在图像相关测量时没有空间变异性。通过图像相关测量的最近7次破裂的滑动分布具有0.09-0.29的短波变异性，这被认为是破裂传播到地表的固有特征。我们的研究结果表明，断裂过程固有的变异性和通过解释引入的变异性都对手工测量的滑移分布的观察变异性有很大贡献。解决在多大程度上短波变异性是通过近地表物质而不是人工解释的破裂传播所固有的，这进一步理解了地表破裂和断层力学之间的关系，并为解释过去地震中的滑动分布和每事件滑动提供了信息。
Slip in strike‐slip earthquakes is spatially variable along a fault, but the degree to which variability over short length scales is inherent to the rupture process or introduced by interpretation and measurement has not been quantified. In this study, we examine the effects of interpretation error on apparent short‐wavelength variability in surface slip distributions by comparing numerical landscape evolution models and recent ruptures on strike‐slip faults measured by hand and with image correlation. Surface slip distributions measured by hand from 63 strike‐slip earthquakes have average spatial variability (CVslip‐spatial = standard deviation/mean) of 0.43–0.52, and a total range of 0.14–1.14. Displacement measurements of offset geomorphic markers from numerical models that simulate constant slip along a fault have average spatial variability of ~0.25–0.40 when measured by hand and no spatial variability when measured by image correlation. Slip distributions from seven recent ruptures measured by image correlation have short‐wavelength variability of 0.09–0.29, which is considered inherent to how rupture propagates to the surface. Our results demonstrate that variability innate to the rupture process and introduced by interpretation both contribute substantially to the observed variability in slip distributions measured by hand. Resolving the extent to which short‐wavelength variability is inherent to rupture propagation through near‐surface material versus an artifact of interpretation furthers understanding of the relationship between surface rupture and fault mechanics and informs interpretation of slip distribution and slip‐per‐event in past earthquakes.